READING QUESTIONS: Atmospheric Moisture
NAME________________________
PSCI 131
DUE: Wednesday, October 14th
Fall 2015
53 pts
All answers should be in your own words.
Water’s Changes of State (p. 224-226)
1. List the six possible state changes for water, and indicate whether each change is exothermic or
endothermic. (6 pts)
State change
Exo- or endothermic
a. _____________________
________________________
b. _____________________
________________________
c. _____________________
________________________
d. _____________________
________________________
e. _____________________
________________________
f. _____________________
________________________
2. What is latent heat? _________________________________________________________________
Humidity: Water Vapor in the Air (p. 226-230)
3. Define saturation as it relates to water vapor in the atmosphere. (2 pts) _________________________
__________________________________________________________________________________
4. What is the saturation content of 1 kilogram of air at the following temperatures? (All temperatures are
in degrees Celsius.) (2 pts)
a. -10
_______ grams
b. 5
_______ grams
c. 20
_______ grams
d. 35
_______ grams
5. What is the relative humidity of 1 kilogram of air at a temperature of 15 degrees C that is holding 7
grams of water vapor? Show all work in a legible and orderly fashion. (4 pts)
Relative humidity: _________ %
6. If the air from the previous question were cooled to a temperature of 10 degrees C, what would its new
relative humidity be? You do not need to show your work for this question.
Relative humidity: __________ %
7. Lowering the temperature of air will cause its relative humidity to _____________, assuming there is no
change in the water vapor content of the air.
8. During a typical 24-hour period, at about what time would you find the highest relative humidity?
_____________________
9. What are the two ways air’s relative humidity can change? (2 pts) ____________________________
_________________________________________________________________________________
10. If air’s relative humidity exceeds 100%, what happens to the excess water vapor? _______________
11. EXTRA CREDIT: Clouds consist of water vapor. TRUE or FALSE
12. Define dew point temperature. (2 pts) ___________________________________________________
__________________________________________________________________________________
13. What was the dew point temperature of the air from question 7? ___________ degrees C
14. Air’s dew point temperature is directly related to
a. The air’s actual temperature
b. The air’s relative humidity
c. The amount of water vapor in the air
d. The air’s saturation content
15. On a warm summer day when the relative humidity is high, it may seem even warmer than the
thermometer indicates. Why does the air feel uncomfortable on these days? (3 pts)
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
The Basis of Cloud Formation: Adiabatic Cooling (p. 230-231)
16. What happens to the temperature of a gas when it expands? ______________
17. Why does air cool when it rises through the atmosphere? _________________________________
18. What is the dry adiabatic rate? Give a definition and give the rate itself. (3 pts) _________________
_________________________________________________________________________________
19. What is the wet adiabatic rate? Give a definition and give the range of rates. (3 pts)
_________________________________________________________________________________
_________________________________________________________________________________
20. Why is the wet adiabatic rate variable? (2 pts) ___________________________________________
_________________________________________________________________________________
21. EXTRA CREDIT: What is the condensation level of air with a starting temperature of 25 degrees C and
a water vapor content of 10g? (1 pt)
________________ meters
22. EXTRA CREDIT: Explain how you arrived at your answer to the last question. (3 pts) _____________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
Processes That Lift Air (p. 232-234)
23. List four mechanisms that cause air to rise. (2 pts)
a. _________________________________
b. _________________________________
c. _________________________________
d. _________________________________
24. Explain how orographic lifting and frontal wedging are similar. (2 pts)
________________________________________________________________________________
________________________________________________________________________________
25. Why does Florida experience more mid-afternoon thunderstorms per year than any other state? (3 pts)
________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
The Weathermaker: Atmospheric Stability (p. 234-237)
26. What is the difference between the environmental lapse rate and the adiabatic cooling rates? (4 pts)
________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
27. Under conditions of absolute stability, why doesn’t air rise unless forced to do so? (2 pts)
______________________________________________________________________________
______________________________________________________________________________
28. What is the most important difference between absolute instability and conditional instability? (2 pts)
______________________________________________________________________________
______________________________________________________________________________